Revert "ios: Enable PA-E checks for metadata corruption issue investigation"

This reverts commit 7a0215d1.

Reason for revert: Revert for weeks 3 and 4 of beta.  See
go/partition-alloc-rollout-v4 for details.

Original change's description:
> ios: Enable PA-E checks for metadata corruption issue investigation
>
> Bug: 371135823
> Change-Id: Ia2d5ed7a9f466be89af144f5f07239151bf05bb8
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5925134


> Commit-Queue: Rohit Rao <rohitrao@chromium.org>
> Auto-Submit: Justin Cohen <justincohen@chromium.org>
> Reviewed-by: Rohit Rao <rohitrao@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1367514}

(cherry picked from commit 682f0aca)

Bug: 371135823
Change-Id: I0f1aa4144a5c945b407579416b5b855a601b0727
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5962418


Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Commit-Queue: Rohit Rao <rohitrao@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Justin Cohen <justincohen@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1373384}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5962480


Commit-Queue: Harry Souders <harrysouders@google.com>
Reviewed-by: Harry Souders <harrysouders@google.com>
Owners-Override: Harry Souders <harrysouders@google.com>
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/branch-heads/6778@{#788}
Cr-Branched-From: b21671ca-refs/heads/main@{#1368529}

ios/features.gni

@@ -14,7 +14,7 @@ declare_args() {
   # Control whether PartitionAlloc for iOS builds has extra checks for
   # metadata corruption issue investigation.
   # TODO(crbug.com/371135823): Remove upon completion of the investigation.
-  ios_partition_alloc_corruption_hardening_enabled = true
+  ios_partition_alloc_corruption_hardening_enabled = false
 
   # Control whether //ios/chrome and //ios/web targets are build. This
   # is used by bots from projects based on top of Chromium that want to